(a) Field of the Invention
The present invention relates to a roll forming system and a roll forming method. More particularly, the present invention relates to a roll forming system and a roll forming method in which cutting and stretch bending of a shaped beam is simultaneously performed in keeping pace with a forming speed of a roll forming after the roll forming.
(b) Description of the Related Art
Generally, a roll forming method is a method in which a coil is uncoiled and the coil is bent to various shapes by passing through a roll forming unit including a plurality of roll formers respectively provided with an upper forming roll and a lower forming roll. The roll forming method is used for manufacturing beams of linear type (particularly, a bumper beam for a vehicle) which is bent to the various shapes.
FIG. 1 is a schematic diagram of a roll forming system according to a conventional art which performs a roll forming method.
As shown in FIG. 1, the roll forming system according to the conventional art includes an uncoiler 201 at a front portion of a process line, and the uncoiler 201 performs an uncoil step S110 at which a coil 200 is uncoiled. A straightener 203 is provided at the rear of the uncoiler 201 and performs a straightening step S120 at which the coil uncoiled from the uncoiler 201 is straightened to a panel 210 of plate shape.
In addition, a brake press 205 is disposed at the rear of the straightener 203 and performs a piercing step S130 at which a plurality of holes for assembling is formed at the panel 210 supplied from the straightener 203.
In addition, a roll forming unit 207 including at least seven roll formers R1-R7 is disposed at the rear of the brake press 205 and performs a roll forming step S140 at which the panel 210 passing through the uncoiler 201, the straightener 203, and the brake press 205 is sequentially bent such that a shaped beam 260 is formed.
A welding unit 209 such as a roll spot welding tool is disposed at the rear of the roll forming unit 207 and performs a welding step S150 at which each welding position of the shaped beam 220 is welded.
In addition, a rounder bender 211 is disposed at the rear of the welding unit 209 and performs a bending step S160 at which the shaped beam 230 delivered from the welding step S150 is formed to have a predetermined curvature.
A cutting press 213 is disposed at the rear of the rounder bender 211 and performs a cutting step S170 at which the shaped beam 240 is cut in a predetermined size.
A finished shaped beam 250, as shown in FIG. 2, is manufactured by the roll forming system.
Recently, a thickness of the shaped beam 250 having a closed section is being increased thicker than 50 mm in order to enhance collision strength.
By the conventional roll forming system, the shaped beam 250 of the closed section having a thickness thinner than 50 mm can be manufactured. In a case that the shaped beam 250 of the closed section having a thickness thicker than 50 mm, deformation at an inner surface of a curvature of the shaped beam 250 is large if the shaped beam 250 is manufactured by the conventional roll forming system. Therefore, buckling may occur at the inner surface of the shaped beam if the bending step S160 is performed by the rounder bender 211.
Therefore, in order to form the shaped beam of closed section having the thickness thicker than 50 mm to have the predetermined curvature, a stretch bending method at which both sides of the shaped beam are pushed to one direction should be used.
However, in order to apply the stretch bending method to the conventional roll forming system, a process speed of the stretch bending should be synchronized with a forming speed of the roll forming of the shaped beam. In addition, a cutting process of the shaped beam should be performed prior to stretch bending.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.